Advice On Creating Grass On Your Roof

Oct 2, 2014 |

Allowing the roof of your house to become a home for living vegetation is something which is desirable nowadays, depending on your location, and can have several benefits to your home. Especially popular in countries like Germany and Scandinavia, and slowing gaining recognition in the United Kingdom, there are two main types of ways to create a green space on your roof:

  • Intensive Green Roofs – Many people would simply call these rooftop gardens, replete with trees and shrubs and thriving plants. A substrate level of about twenty centimetres is required to grow plants on a rooftop, and it is imperative to have the impact a rooftop garden will have on the structure of your home assessed by a qualified professional, before undertaking any work at all. Having a rooftop garden can add considerable weight to the rooftop it is located on.
  • Extensive Green Roofs – This is the more popular way of achieving a green roof, as it needs just a few centimetres of soil layer to successfully install grass and shrubs, making it much less of a weight for the roof to bear, and needs less attention than an actual rooftop garden. The turf can be rolled out and into place quickly and easily, and this method is inexpensive compared to the cost of creating a full garden, but you can still enjoy the benefits of an open air green space on your roof.

How To Grow Grass On Your Roof

Large Grassland AreaIf you choose to go through the pleasurable process of growing your own rooftop grass rather than purchasing pre-grown rolls of turf, a little preparation and understanding is required. Assuming that your roof has a pitch of between five and twenty degrees – giving a small slope – and that you have looked into whether or not you need to buy a licence or permit, or ask for permission to create a vegetated roof, the following steps will help you to create a green roof:

  1. Measure the intended area to be used, so that you know how much underlay you need to purchase. The underlay acts as the barrier between the roof and the grass, and should be of quality.
  2. Buy the correct amount of underlay from a reputable dealer, the underlay should have some layers of insulation, moisture barriers, drainage protection and filter fabric. Read and follow the manufacturer’s instructions on how to install.
  3. Purchase the correct amount of sod (sod is pre-planted grass that can be planted and grown, giving lush grass. It is more popular than growing from seed as it is much more reliable) and either plant it immediately, or place in a cool area. Make sure to keep moisturised until ready to plant.
  4. Lay the underlay, and cover with a one inch layer of good quality compost, and rake it until it is smooth, and then add a sparse layer of gravel, raked, to improve drainage. On top of this, add another raked one inch level of potting soil.
  5. Lay the pieces of sod, and try to use the longer pieces if possible, as there is a greater chance they will survive. Trim or cut into shape with a sharp knife, and use the smaller pieces in the centre of the area, not at the edges.
  6. Lightly water the laid sod immediately, the idea is to lessen the shock by giving them water. This usually works well, and the grass responds.
  7. Keep watering the rooftop grass every couple of weeks in the growing season, as it cannot fully build up the extensive underground root systems it normally can at ground level.

Are There Any Other Factors To Consider Regarding Rooftop Grass?

There is some equipment you will need to have in order to carry out the above steps:

  • Tape measure
  • Spirit level
  • Underlay system
  • Compost/potting soil
  • Gravel
  • Rake
  • Sod
  • Utility knife
  • Water and watering can.

The other factor is the weather. On rooftops of taller buildings, the sun can be stronger and the wind can be harsher than at ground level. Care is needed if you are intending to use pre planted sod, but if you are planning to grow your green roof from seed, you will need to take external factors into consideration. Care and protection should be given to grass grown from seed, and in the early stages it might be beneficial to install windbreakers onto the roof, to lessen the effect of the wind. The can be built or bought in such a way so as to include protection from strong sunlight as well. Remember that grass growing on a rooftop will require more care and watering than grass at ground level.

Following the above steps will allow you to create a low-maintenance yet enjoyable and relaxing green roof. Many people do not have the time to invest into creating intense rooftop gardens, and instead seek to create an outside place that has the green and peaceful effect of a park or beauty spot, without all the intense labour. Growing grass, and perhaps having some shrubs and small plants for brightness and colour, or a table and chairs to relax on is easy and satisfying to do, and with a little research, is attainable for everyone who is in a position to take advantage of their rooftop space.

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